Vision is involved intimately with almost every aspect of a person's daily life. If a person's vision deteriorates then usually so does the person's quality of life.
Vision can be divided into three conceptual layers, seen generally in FIG. 1. An optical layer 100 provides for the focusing of light onto a photosensitive layer of tissue at the back of the eye, called the retina. A functional layer 102 (formed by the retina) contains photosensitive cells which can detect various colors, motion and form, and converts these to nervous impulses which are sent to the brain. The third layer is a perceptual layer 106 which is a part of the brain that constructs a picture from the light information sent from the eyes.
During the last century, many tests have been developed to measure aspects of the vision process, and three groups of professionals: optometrists, ophthalmologists and neurologists, have had the responsibility divided among them for carrying out the tests and treating the problems involved.
Optometrists are scientifically qualified and, in general, measure and treat problems associated with the optical layer 100. As optometrists are usually the first to deal with a patient having a vision problem, optometrists often detect problems in the functional and perceptual layers 102, 106. If a pathological problem arises in area 102 or 106, optometrists generally refer patients to the professionals best qualified to treat these problems. Ophthalmologists are medically qualified and normally measure and treat problems involving both the optical layer 100 and the functional layer 102. This group of professionals will typically diagnose and treat diseases of the eye. Problems occurring in the perceptual layer 106 caused by other diseases affecting the visual process are usually referred to a neurologist. Neurologists are psychiatrically and medically qualified, and treat the problems occurring at the perceptual layer 106 when the vision process is affected by other perturbing abnormalities in the patient's brain.
It is routine for people experiencing some vision problem to visit an optometrist to have their eyes examined. The equipment used by the optometrist for examination is mainly lens-based. Since such equipment is often heavy, bulky and very sensitive, it is generally not suitable for transport. Such equipment is often quite expensive. Consequently people who lack mobility, or who live a long way from cities or large towns, have been disadvantaged through lack of optometric servicing. When optometrists do travel, generally only a small number of lenses are used for diagnostic purposes, and as such, the examination conducted may not be as thorough as one performed with the aid of the typical equipment mentioned above.
It is therefore desirable for optical examinations to be performed without reliance upon bulky, generally immobile and expensive equipment.